It was announced exclusively on "Good Morning America" that the former dancing pro will serve as a guest judge on Monday, Oct. 12.
Chmerkovskiy, 35, will appear on the panel alongside judges Carrie Ann Inaba, Bruno Tonioli and Julianne Hough. He left DWTS last June after appearing on the show since Season 2.
The one-time "Dancing" champion said earlier this year that he'll never again compete for the Mirrorball trophy.
"You have to walk away when the time is right, and the time was right," he told Glamour magazine in May. "Nothing was out of ordinary. I think the change of guard is necessary. Like a plant that in order to improve growth, you have to pull branches. It’s the same thing."